Improve error message for illegal part of declarations

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 6044 matching lines @@
   } else {
     ASSERT(is_export);
     library_.AddExport(ns);
   }
 }
 
 
 void Parser::ParseLibraryPart() {
   const TokenPosition source_pos = TokenPos();
   ConsumeToken();  // Consume "part".
+  if (IsSymbol(Symbols::Of())) {
+    ReportError("part of declarations are not allowed in script files");
+  }
   CheckToken(Token::kSTRING, "url expected");
   AstNode* url_literal = ParseStringLiteral(false);
   ASSERT(url_literal->IsLiteralNode());
   ASSERT(url_literal->AsLiteralNode()->literal().IsString());
   const String& url = String::Cast(url_literal->AsLiteralNode()->literal());
   ExpectSemicolon();
   const String& canon_url = String::CheckedHandle(
       CallLibraryTagHandler(Dart_kCanonicalizeUrl, source_pos, url));
   CallLibraryTagHandler(Dart_kSourceTag, source_pos, canon_url);
 }
@@ skipping 8532 matching lines @@
     const ArgumentListNode& function_args,
     const LocalVariable* temp_for_last_arg,
     bool is_super_invocation) {
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME